Avian nephritis virus
Avian nephritis virus (ANV) is an astrovirus which causes 'avian nephritis' in chickens. There are actually two strains that affect chickens--avian nephritis virus 1 (ANV-1) and avian nephritis virus 2 (ANV-2). Astroviruses are classified within the unassigned Astroviridae family and are non-enveloped viruses characterized by a positive sense, single-stranded RNA (ssRNA) genome.
In birds, astrovirus infection may be asymptomatic or associated with enteric disease and a range of other symptoms indicative of the involvement of other organ systems including hepatitis and nephritis. Transmission occurs via the fecal-oral route, bird-to-bird contact, or contaminated food or water.